Convert.ToDouble Method (Object)

Parameters

• value
  Type: System.Object
  An Object that implements the IConvertible interface or nulla null reference (Nothing in Visual Basic).

Return Value

Type: System.Double
A double-precision floating point number equivalent to the value of value, or zero if value is nulla null reference (Nothing in Visual Basic).

Public Sub ConvertDoubleString(ByVal doubleVal As Double)

   Dim stringVal As String

   ' A conversion from Double to String cannot overflow.       
   stringVal = System.Convert.ToString(doubleVal)
   outputBlock.Text &= String.Format("{0} as a String is: {1}", _
                             doubleVal, stringVal) & vbCrLf

   Try
      doubleVal = System.Convert.ToDouble(stringVal)
      outputBlock.Text &= String.Format("{0} as a Double is: {1}", _
                                stringVal, doubleVal) & vbCrLf
   Catch exception As System.OverflowException
      outputBlock.Text &= String.Format( _
          "Overflow in String-to-Double conversion.") & vbCrLf
   Catch exception As System.FormatException
      outputBlock.Text &= String.Format( _
          "The string is not formatted as a Double.") & vbCrLf
   Catch exception As System.ArgumentException
      outputBlock.Text &= "The string is null." & vbCrLf
   End Try

End Sub

public void ConvertDoubleString(double doubleVal)
{
   string stringVal;

   // A conversion from Double to string cannot overflow.       
   stringVal = System.Convert.ToString(doubleVal);
   outputBlock.Text += String.Format("{0} as a string is: {1}",
      doubleVal, stringVal) + "\n";

   try
   {
      doubleVal = System.Convert.ToDouble(stringVal);
      outputBlock.Text += String.Format("{0} as a double is: {1}",
         stringVal, doubleVal) + "\n";
   }
   catch (System.OverflowException)
   {
      outputBlock.Text += String.Format(
         "Conversion from string-to-double overflowed.") + "\n";
   }
   catch (System.FormatException)
   {
      outputBlock.Text += String.Format(
         "The string was not formatted as a double.") + "\n";
   }
   catch (System.ArgumentException)
   {
      outputBlock.Text += String.Format(
         "The string pointed to null.") + "\n";
   }
}